Aerosol-generating article comprising an aerosol-cooling element

ABSTRACT

An aerosol-cooling element ( 100 ) for an aerosol-generating article. The aerosol-cooling element ( 100 ) comprises an interior structure ( 102 ) and a wrapper material ( 104 ) secured around the interior structure ( 102 ). The wrapper material ( 104 ) comprises a first portion ( 106 ) welded to a second portion ( 108 ) of the wrapper material ( 104 ).

This application is a U.S. National Stage Application of InternationalApplication No. PCT/EP2019/051672 filed Jan. 23, 2019, which waspublished in English on Aug. 15, 2019 as International Publication No.WO 2019/158335 A1. International Application No. PCT/EP2019/051672claims priority to European Application No. 18157001.1 filed Feb. 15,2018.

The present invention relates to aerosol cooling elements foraerosol-generating articles and to methods of their manufacture. Inparticular, the present invention relates to aerosol-cooling elementscomprising a wrapper material secured by welding.

Aerosol-generating articles may comprise a plurality of elementsassembled in the form of a rod. These elements may include anaerosol-forming substrate and an aerosol-cooling element locateddownstream from the aerosol-forming substrate.

As used herein, the term ‘rod’ is used to denote a generally cylindricalelement of substantially circular, oval or elliptical cross-section.

As used herein, the term ‘longitudinal direction’ refers to a directionextending along, or parallel to, the cylindrical axis of a rod.

The terms “upstream” and “downstream” may be used to describe relativepositions of elements or components of the aerosol-generating article.For simplicity, the terms “upstream” and “downstream” as used hereinrefer to a relative position along the rod of the aerosol-generatingarticle with reference to the direction in which the aerosol is drawnthrough the rod.

The manufacture of aerosol-generating articles comprisingaerosol-cooling elements may include forming raw material into a sheet.The sheet may then be crimped between two rollers to introduce parallellines of weakness into the sheet. The crimped sheet may then be gatheredinto a rod by folding the sheet about the lines of weakness to form therod with an internally pleated structure. This may be achieved bypulling the crimped sheet material through a funnel to compress thesheet into a continuous rod having a diameter approximately the diameterof the final tubular rod. The continuous rod may then be wrapped in awrapper. The wrapper may be wrapping paper or other suitable wrappingmaterial. For example, glue may be applied to one edge of the wrapper sothat it can be wrapped around the continuous rod. The wrapped continuousrod may be compressed into a final desired shape while being heated todry the applied glue. The wrapped continuous rod may then be cut intorods of smaller length to produce cooling elements of a desired lengthfor use in aerosol-generating articles. The cooling elements describedabove have a large internal surface area that may provide enhancedthermal exchange between the cooling element and aerosol moving throughit.

The manufacture of aerosol-generating articles comprisingaerosol-cooling elements can present several problems during productionand in the finished article. One potential problem, which may beworsened by a high-mechanical resistance to compression of the sheetmaterial, is that the glue may fail to hold the wrapper around the rod.This can lead to expansion of the wrapper over time and, thus, a failurein a control of a diameter of the rod. Furthermore, the wrapper seam maycome apart completely. This can cause problems in later processes wherea faulty rod may jam downstream equipment. For example, the combiner,which combines the elements of an aerosol-generating article andassembles them into the article can become jammed by unravelled orexpanded aerosol-cooling elements.

Another potential problem is glue pollution, where surplus glue from theseal may contaminate downstream equipment.

It is an object of the present invention to mitigate one or moreproblems associated with the manufacture of aerosol-cooling elements.

According to one aspect of the invention there is provided anaerosol-cooling element for an aerosol-generating article, theaerosol-cooling element comprising:

an interior structure formed by crimping and folding a sheet material toform a cylindrical rod, the cylindrical rod having an averagecircumference of C1 in the absence of any external compressive forces;and

a wrapper material secured around the interior structure to form a rodwith a predetermined circumference C2;

wherein the wrapper material comprises a first portion welded to asecond portion of the wrapper material;

wherein the interior structure is under compression by the wrappermaterial when the wrapper material is secured around the interiorstructure;

and wherein C1/C2 is in a range from 1.2 to 6.

In some embodiments, C1/C2 is in a range from 1.3 to 4. In someembodiments, C1/C2 is in a range from 1.4 to 2.5.

The average circumference is determined by measuring the averagecircumference of the cylindrical rod formed after the sheet material hasbeen crimped and gathered. C1 is determined on a test bench by passing asheet identical to that used on a production line through a funnelstructure of the same dimensions as that used on the production line,without wrapping the gathered sheet. C1 is measured after the passing ofa predetermined time of 2 minutes, after the sheet material has beengathered and folded. This is in order to allow the gathered and foldedsheet material to settle into an uncompressed gathered state. C1 is thenmeasured by way of a measuring tape passed around the cylindrical rodformed after the sheet material has been crimped and folded, taking carenot to compress the cylindrical rod with the measuring tape whilemeasuring C1.

C2 is measured by measuring the circumference of the rod formed by thewrapper material secured around the interior structure in the same wayas C1.

The wrapper is welded around the interior structure, rather than by theapplication of glue, thereby addressing problems associated with a gluedseam in the wrapper material.

Because C2 is less than C1, it will be understood that the interiorstructure is under compression by the wrapper. As such, the interiorstructure will tend to exert an outward force on the wrapper.Accordingly, using a known glued seam in the wrapper material would beproblematic, because the outward force could cause the seam to comeapart before the glue had set.

This problem may be addressed by compressing the interior structure andthe wrapper material when securing the wrapper material around theinterior structure by welding the first portion of the wrapper materialto the second portion of the wrapper material.

As used herein, the term ‘welded’ may refer to any form of bonding orfusing, where heat is applied to cause a bond with the absence of anadhesive. In a non-limiting example, welding may include at leastpartially melting a material.

As used herein, the term ‘aerosol-generating article’ refers to anarticle comprising an aerosol-forming substrate that is capable ofreleasing volatile compounds that can form an aerosol, for example byheating, combustion or a chemical reaction.

As used herein, the term ‘aerosol-forming substrate’ is used to describea substrate capable of releasing volatile compounds, which can form anaerosol. The aerosols generated from aerosol-forming substrates ofaerosol-generating articles according to the invention may be visible orinvisible and may include vapours (for example, fine particles ofsubstances, which are in a gaseous state, that are ordinarily liquid orsolid at room temperature) as well as gases and liquid droplets ofcondensed vapours.

As used herein, the term ‘aerosol-cooling element’ is used to describean element having a large surface area and a predetermined resistance todraw. In use, an aerosol formed by volatile compounds released from theaerosol-forming substrate passes over and is cooled by theaerosol-cooling element before being inhaled by a user. In contrast tohigh resistance to draw filters and other mouthpieces, aerosol-coolingelements have a low resistance to draw. Chambers and cavities within anaerosol-generating article are also not considered to be aerosol coolingelements.

As used herein, the terms ‘sheet’ and ‘web’ denote a laminar elementhaving a width and length substantially greater than the thicknessthereof.

As used herein, the term ‘corrugated’ denotes a sheet or web with aplurality of corrugations, undulations or striations oriented insubstantially the same direction.

As used herein, the term ‘corrugations’ denotes a plurality ofsubstantially parallel ridges formed from alternating peaks and troughsjoined by corrugation flanks. This includes, but is not limited to,corrugations having a square wave profile, sinusoidal wave profile,triangular profile, sawtooth profile, or any combination thereof.

As used herein, the term ‘crimped’ denotes a sheet or web with aplurality of corrugations.

As used herein, the terms ‘gathered’ or ‘gathering’ denote that a web orsheet is convoluted, or otherwise compressed or constrictedsubstantially transversely to the cylindrical axis of the rod.

Aspects of the invention do not require prior application of a glue tothe wrapper material. Furthermore, welding may be achieved at a quickerrate than glue which may require curing or uniform application ofpressure.

The interior structure may comprise a crimped, pleated or folded sheetmaterial. Advantageously, this increases the surface area of theinterior structure which may increase its cooling ability.

The first portion of the wrapper material may be a region contiguous andparallel to a first edge of the wrapper material, and the second portionmay be a region contiguous and parallel to a second edge of the wrappermaterial. Advantageously, this may provide a uniform, symmetric coolingelement.

The interior structure may comprise a longitudinal axis and the secondedge of the wrapper material may be aligned at a non-zero angle to thelongitudinal axis.

The first portion may be welded to the second portion via a conductiveelement. In embodiments, the conductive element may comprise a metallicstrip. In embodiments, the conductive element may be in contact with thefirst or second portion, or may be arranged between the first and secondportions. The conductive element may conduct heat to the first and/orsecond portion to induce welding of the first portion to the secondportion. Advantageously, this may increase ease and/or speed of thewelding.

The first portion may be induction welded to the second portion.Induction welding uses electromagnetic induction to heat a conductiveelement. This may provide a quick and optionally contactless process forwelding the first portion to the second portion.

Alternatively, the first portion may be ultrasonically welded to thesecond portion. Ultrasonic welding may use high frequency vibrations toweld one portion to another. The vibrations may be applied by asonotrode for example. Advantageously, this may provide a quick methodof welding that does not require the presence of a conductive element.

The aerosol-cooling element may have a length between 7 mm and 28 mm, oroptionally from 10 to 25 mm, or optionally from 13 to 22 mm, optionallyfrom 16 to 19 mm.

The aerosol-cooling element may have a diameter between 5 mm and 12 mm,optionally from 6 to 9 mm, or optionally from 7 to 8 mm.

The wrapper material may comprise a thermoplastic polymer.Advantageously, a thermoplastic polymer may be readily welded to itselfto provide a strong seal. Furthermore, polymeric materials can beformulated to have a melting point optimised for a particular weldingprocess. Optionally, the interior structure may comprise polylacticacid.

The first portion and/or second portion of the wrapper may comprise anadditional material that can be melted or heated to induce tack. Theadditional material may be in the form of one or more regions added tothe wrapper, e.g. a thermoplastic strip added to the first portionand/or second portion of the wrapper. The additional material may allowwelding of wrappers formed from material that cannot conventionally bewelded, or may further improve the welding performance of a wrapper.

According to another aspect of the invention there is provided anaerosol-generating article, the aerosol-generating article comprisingany aerosol-cooling element in accordance with any aspect describedherein.

The aerosol-generating article may comprise an aerosol-forming substrateand the aerosol-cooling element may be located downstream of theaerosol-forming substrate.

According to another aspect of the invention there is provided a methodfor manufacturing an aerosol-cooling element for an aerosol-generatingarticle, the method comprising:

providing an interior structure of the aerosol-cooling element bycrimping and folding a sheet material into a rod shape;

wrapping the interior structure of the aerosol-cooling element with awrapper material;

securing the wrapper material around the interior structure by welding afirst portion of the wrapper material to a second portion of the wrappermaterial; and

compressing the interior structure and wrapper material when securingthe wrapper material around the interior structure.

Providing the interior structure may comprise forming a sheet materialinto a rod shape. Forming a sheet material into a rod shape may comprisecrimping the sheet material, and/or pleating or folding the sheetmaterial. Pleating or folding the sheet material may comprise passingthe sheet material through a funnel having an outlet diameter similar tothat of the desired rod shape.

The first portion of the wrapper material may be a region contiguous andparallel to a first edge of the wrapper material and the second portionmay be a region contiguous and parallel to a second edge of the wrappermaterial.

The interior structure may comprise a longitudinal axis; and wrappingthe interior structure of the aerosol-cooling element may compriseplacing the second edge in contact with the interior structure and at anon-zero angle to the longitudinal axis, and placing the first edge overthe second edge.

The method of manufacturing an aerosol-cooling element may furthercomprise placing a conductive element between the first portion andsecond portion of the wrapper material; and heating the conductiveelement to at least partially melt the first portion of the wrappermaterial. Optionally the conductive element may be placed in contactwith one of the first portion or the second portion only, to weld oneportion to the other.

The method may comprise welding by induction welding. This may compriseinducing a current in a conductive element to melt a portion of thewrapper. Alternatively, the method may comprise welding by ultrasonicwelding. Ultrasonic welding may comprise using a sonotrode to at leastpartially melt the wrapper material.

The method of manufacturing an aerosol-cooling element may furthercomprise compressing the interior structure and wrapper material whensecuring the wrapper around the interior structure.

According to another aspect of the invention there is provided a methodfor manufacturing an aerosol-generating article, the method comprisingmanufacturing an aerosol-cooling element according to the foregoingaspects of the invention; and incorporating the aerosol-cooling elementinto the aerosol-generating article.

The method may additionally comprise incorporating an aerosol-formingsubstrate in the aerosol-generating article, and incorporating theaerosol-cooling element downstream of the aerosol-forming substrate.

According to another aspect of the invention there is provided anapparatus for manufacturing an aerosol-cooling element for anaerosol-generating article, the apparatus comprising:

a gathering unit to gather and fold a supply of crimped sheet materialinto a rod shaped interior structure for the aerosol-cooling element rodshape;

a wrapping unit to wrap the interior structure about a longitudinal axisof the rod shape with a wrapper material and to secure the wrappermaterial around the interior structure by welding a first portion of thewrapper material to a second portion of the wrapper material; and acompressing unit to compress the interior structure and wrapper materialwhen securing the wrapper material around the interior structure.

It will be appreciated that preferred features described above inrelation to one aspect of the invention may also be applicable to otheraspects of the invention

Embodiments of the invention will now be described, by way of exampleonly, with reference to the accompanying drawings.

FIG. 1 shows a schematic diagram of an aerosol-cooling element accordingto an embodiment of the present invention;

FIG. 2 shows a schematic diagram of a longitudinal cross section throughan aerosol-generating article comprising the aerosol-cooling elementaccording to an embodiment of the present invention;

FIG. 3 shows a schematic diagram of an apparatus for production ofaerosol-cooling elements according to an embodiment of the presentinvention;

FIG. 4 shows a flow chart of a method of manufacturing theaerosol-cooling elements according to an embodiment of the presentinvention;

FIG. 5 shows a flow chart of a method of securing the wrapper materialaccording to an embodiment of the present invention;

FIG. 6 shows a flow chart of a method of securing the wrapper materialaccording to another embodiment of the present invention; and

FIG. 7 shows a flow chart of a method of securing the wrapper materialaccording to a further embodiment of the present invention.

The present invention relates to an aerosol-cooling element for anaerosol-generating article. Aerosol-generating articles in which anaerosol-forming substrate, such as a tobacco containing substrate, isheated rather than combusted are known in the art. Examples of systemsusing aerosol-generating articles include systems that heat a tobaccocontaining substrate above 200 degrees Celsius to produce anicotine-containing aerosol.

The aerosol-cooling element may act to cool the temperature of a streamof aerosol drawn through the element by means of thermal transfer.Components of the aerosol will interact with the aerosol-cooling elementand lose thermal energy.

The aerosol-cooling element may act to cool the temperature of a streamof aerosol drawn through the element by undergoing a phasetransformation that consumes heat energy from the aerosol stream. Forexample, the material forming the aerosol-cooling element may undergo aphase transformation such as melting or a glass transition that requiresthe absorption of heat energy. If the element is selected such that itundergoes such an endothermic reaction at the temperature at which theaerosol enters the aerosol-cooling element, then the reaction willconsume heat energy from the aerosol stream.

In some embodiments, the temperature of an aerosol stream may be loweredby more than 10 degrees Celsius as it is drawn through anaerosol-cooling element. In some embodiments, the temperature of anaerosol stream may be lowered by more than 15 degrees Celsius or morethan 20 degrees Celsius as it is drawn through an aerosol-coolingelement.

FIG. 1 shows a schematic diagram of an aerosol-cooling element 100 foran aerosol-generating article according to an embodiment of the presentinvention. Aerosol-cooling element 100 comprises an interior structure102 and a wrapper material 104 secured around the interior structure102. The wrapper material 104 comprises a first portion 106 welded to asecond portion 108 of the wrapper material 104.

The interior structure 102 comprises a crimped, pleated or folded sheetmaterial.

As used herein, the term ‘crimped’ denotes a sheet having a plurality ofsubstantially parallel ridges or corrugations. Preferably, when theaerosol-generating article has been assembled, the substantiallyparallel ridges or corrugations extend in a longitudinal direction withrespect to the rod. As used herein, the terms ‘gathered’, ‘pleated’, or‘folded’ denote that a sheet of material is convoluted, folded, orotherwise compressed or constricted substantially transversely to thecylindrical axis of the rod. A sheet may be crimped prior to beinggathered, pleated or folded. A sheet may be gathered, pleated or foldedwithout prior crimping.

In some embodiments, the sheet material may comprise a sheet materialselected from the group comprising a metallic foil, a polymeric sheet,and a substantially non-porous paper or cardboard. In some embodiments,the aerosol-cooling element may comprise a sheet material selected fromthe group consisting of polyethylene (PE), polypropylene (PP),polyvinylchloride (PVC), polyethylene terephthalate (PET), polylacticacid (PLA), cellulose acetate (CA), and aluminium foil.

The internal structure 102 fabricated from a crimped, pleated or foldedmaterial sheet increases the surface area of the internal structure and,thus, the ability of the internal structure 102 to cool aerosol passingthrough it.

The internal structure 102 may be formed from a sheet material that hasa specific surface area of between about 10 square millimetres permilligram (mm²/mg) and about 100 square millimetres per milligram(mm²/mg). In some embodiments, the specific surface area may be about 35mm²/mg. Specific surface area can be determined by taking a materialhaving a known width and thickness. For example, the material may be apolylactic acid material having an average thickness of 50 micrometreswith a variation of ±2 micrometres. Where the material also has a knownwidth, for example, between about 200 millimetres and about 250millimetres, the specific surface area and density can be calculated.

The first portion 106 of the wrapper material 104 is a region contiguousand parallel to a first edge 110 of the wrapper material 104 and thesecond portion 108 is a region contiguous and parallel to a second edge112 of the wrapper material 104.

The interior structure 102 has a longitudinal axis. The second edge 112of the wrapper material 104 is aligned at a non-zero angle 116 to thelongitudinal axis. For example, the second edge 112 may be at an angle116 (to the longitudinal axis) of about 20 degrees, 30 degrees or 40degrees.

The first portion 106 may be melt-bonded to the second portion 108 via ametallic strip (not shown). Alternatively, the first portion 106 may beinduction welded to the second portion 108. The first portion 106 may beultrasonically welded to the second portion 108.

The aerosol-cooling element 100 may have a length 114 between 7 mm and28 mm and may have a diameter 118 between 5 mm and 12 mm.

The wrapper material 104 may comprise, or be made, from a polymer. Insome examples, the interior structure 102 comprises, or is made, frompolylactic acid.

FIG. 2 shows a cross sectional diagram of an aerosol-generating article200 comprising the aerosol-cooling element 100 of FIG. 1. Theaerosol-generating article 200 further comprises an aerosol-formingsubstrate 204 and a filter 206. The aerosol-cooling element 100 islocated downstream of the aerosol-forming substrate 204 and upstream ofthe filter 206.

The elements of the aerosol-generating article 200 are preferably heldtogether by means of a suitable wrapper, for example a tipping paper.The tipping paper may comprise any suitable material for wrappingcomponents of the aerosol-generating article 200 in the form of a rod.The tipping paper needs to grip the component elements of theaerosol-generating article 200 when the article 200 is assembled andhold them in position within the rod. Suitable materials are well knownin the art.

The aerosol-generating article 200 may have a total length betweenapproximately 30 mm and approximately 100 mm. The aerosol-generatingarticle 200 may have an external diameter 208 between approximately 5 mmand approximately 12 mm. The filter 206 may be located at the downstreamend of the aerosol-generating article 200. The filter 206 may be acellulose acetate filter plug. The filter 206 may be approximately 7 mmin length in one embodiment, but may have a length of betweenapproximately 5 mm and approximately 10 mm. The aerosol-generatingarticle 200 may comprise a spacer element (not shown) located downstreamof the aerosol-forming substrate 204. In one example, theaerosol-generating article 200 has a total length of approximately 45mm. The aerosol-generating article 200 may have an external diameter 208of approximately 7.2 mm. Further, the aerosol-forming substrate 204 mayhave a length of approximately 10 mm. Alternatively, the aerosol-formingsubstrate 204 may have a length of approximately 12 mm. Further, thediameter of the aerosol-forming substrate 204 may be betweenapproximately 5 mm and approximately 12 mm.

FIG. 3 shows a schematic diagram of an apparatus 300 for production ofthe aerosol-cooling elements 100 according to an embodiment of thepresent invention. Apparatus 300 comprises a crimping apparatus 302which produces a continuous crimped internal structure 102, a materialbobbin 304, which dispenses a layer of material around the continuousinternal structure 102, a heat and press unit 306 and a cutting unit308.

FIG. 4 shows a flow chart of a method 400 of manufacturing theaerosol-cooling elements 100 according to an embodiment of the presentinvention. In the method 400, the interior structure is provided 404 bycrimping, pleating or folding 402 a sheet material into a continuous rodshaped interior structure 102. The interior structure 102 is wrapped 406with a wrapper material 310. The wrapper material 310 is then secured408 around the continuous interior structure 102 by welding a firstportion 106 of the wrapper material 310 to a second portion 108 of thewrapper material 310. The first portion 106 of the wrapper material 310is a region contiguous and parallel to a first edge 110 of the wrappermaterial 310 and the second portion 108 is a region contiguous andparallel to a second edge 112 of the wrapper material 310.

The continuous interior structure 102 has a longitudinal axis. Wrapping406 the continuous interior structure 102 comprises placing the secondedge 112 in contact with the continuous interior structure 102 and at anon-zero angle 114 to the longitudinal axis, and placing the first edge110 over the second edge 112.

The continuous interior structure 102 and wrapper material 310 arecompressed 410 to secure the wrapper material 310 around the continuousinterior structure 102. The wrapped continuous interior structure 102 isthen processed by the cutting unit 308 wherein it is cut 412 into theaerosol-cooling elements 100 of desired length 114, as shown in FIG. 1.

FIG. 5 shows a flow chart of a method 408A of securing the wrappermaterial 310 by melt-bonding according to an embodiment of the presentinvention.

In method 408A the second portion 108 is folded on an outside surface ofthe first portion 106. Heat from the heating and pressing unit 306 isadjusted to melt 508 the first and second portions 106, 108. With regardto FIG. 4, the melted portions 106, 108 are then compressed 410. Duringcompression 410, the first and second portions 106, 108 are caughtbetween the heating and pressing unit 306 above and the continuousinternal structure 102 below. The continuous internal structure 102 canact as a backing block due to its resistance to compression. The wrappermaterial 310 is held and/or pressed by the heating and pressing unit 306until the first and second portions 106, 108 have at least partiallyre-solidified.

In some examples, method 408A further comprises placing 504 a metallicmaterial between the first portion 106 and second portion 108 of thewrapper material 310 and heating 506 the metallic material to at leastpartially melt the first portion 106 of the wrapper material 310.

The shape of a heating part of the heating and pressing unit 306 may beconcave with a diameter in the range of an average diameter of theaerosol-cooling element 100. The heating part may also be smooth so thatthe heated wrapper material 310 remains smooth and cylindrical.Furthermore, the heating and pressing unit 306 may have an outsidecoating made from a non-stick material to prevent any wrapper material310 having too much friction resistance or grip on the heating partsurface. This is especially likely when the wrapper material is in amolten state. In some example, the outside coating is made frompolytetrafluoroethylene (PTFE) or a similar material.

FIG. 6 shows a flow chart of an alternative method 408B of securing thewrapper material 310 using induction welding according to an embodimentof the present invention. In the method of securing the wrapper material310 according to method 408B, the heating and pressing unit 306comprises an induction heater. The induction heater comprises anelectromagnet and an electronic oscillator that passes a high-frequencyalternating current through the electromagnet. A thin conductive film isplaced 602 between the first portion 106 and the second portion 108. Thethin conductive film may be lightly glued 604 such that it stays in thecorrect position during the induction welding. An alternating current ispassed through coils to generate 606 an alternating magnetic field. Anarea where the first portion 106, the conductive film and the secondportion 108 are located is passed 608 inside the alternating magneticfield. The alternating magnetic field penetrates the film which induces610 electric eddy currents in the film. The electric eddy currentsflowing through the resistance of the film generate heat 612. Thegenerated heat melts 614 the first portion 106 and the second portion108 of the wrapper material 310. With regard to FIG. 4, the melted firstand second portions 106, 108 are then compressed 410 together by theheating and pressing unit 306 until they have at least partiallyre-solidified.

FIG. 7 shows a flow chart of another alternative method 408C of securingthe wrapper material 310 using ultrasonic welding according to anembodiment of the present invention. In the method of securing thewrapper material 310 according to method 408C, the heating and pressingunit 306 comprises a sonotrode. Method 408C comprises folding 702 thesecond portion 108 on the outside surface of the first portion 106. Thefirst and second portions are held 704 between the continuous internalstructure 102 and/or heating and pressing unit and the sonotrode. Thesonotrode is connected to a transducer such that high-frequency acousticvibrations are emitted 706. Resulting vibrations are absorbed 708 by thefirst and second portions 106, 108 causing them to melt. With regard toFIG. 4, the melted first portion 106 and second portion 108 are thencompressed 410 until they have at least partially re-solidified.

The wrapper material 310 may comprise or be made from a thermoplasticfilm such as a polylactic acid film. The continuous interior structure102 may comprise or be made from a material resistant to compressionsuch as polylactic acid.

With reference to FIG. 2, a method for manufacturing theaerosol-generating article 200 may comprise incorporating anaerosol-forming substrate 204, a filter 206 and the aerosol-coolingelement 100 into a rod, wherein the aerosol-cooling element 100 isincorporated downstream of the aerosol-forming substrate 206.

In some embodiments, the filter 206 is a conventional mouthpiece filterformed from cellulose acetate. The filter 206 may have a length of about45 millimetres.

Heat from the welding methods 408A, 408B and 408C could alter an outsidesurface of the aerosol-cooling element 100. However, the outside surfaceof the aerosol-cooling element 100 may be covered by at least onetipping paper in the final aerosol-generating article 200. This tippingpaper is usually used to hold elements of the aerosol-generating article200 together. Thus, any slight alterations or imperfections of theoutside surface of the aerosol-cooling element 100 need not be visiblein the final aerosol-generating article 200.

The aerosol-cooling element 100 may act to cool the temperature of astream of aerosol drawn through the element by means of thermaltransfer. Components of the aerosol will interact with theaerosol-cooling element 100 and lose thermal energy.

The aerosol-cooling element 100 derived from method 400 with the methodof securing 408 the wrapper material 310 by welding according to methods408A, 408B or 408C has the advantage that the wrapper material 310 isheld by welding of the wrapper material itself as opposed to being heldby a glue. Replacing gluing with the stronger holding mechanism ofwelding alleviates issues with the gluing not being strong enough tohold the sheet material, which may be highly resistant to mechanicalcompression, in a cylinder.

Thus, the associated problems that may result from gluing such as:expansion of the wrapper material, the cylinder unravelling, diametercontrol failure and glue pollution in equipment associated with themanufacture can be alleviated.

Another advantage of the present invention is that there is no need forsubstantially modification of existing equipment used in the manufactureof aerosol-generating articles. This has the effect that the methoddescribed herein of manufacturing aerosol-generating articles can beeasily and cost effectively incorporated into current equipment andsystems with only minor variations required. Processes wherein theequipment may not need to be modified to realise the method ofmanufacturing aerosol-generating articles as described herein include:equipment for the crimping process 302, equipment for the supplying thewrapper material 310, such as a bobbin, and equipment for cutting therods 308. This has the advantage of keeping implementation costs low.

The invention claimed is:
 1. An aerosol-cooling element for anaerosol-generating article, the aerosol-cooling element comprising: aninterior structure formed by crimping and folding a sheet material toform a cylindrical rod, the cylindrical rod having a circumference C1 inthe absence of any external compressive forces; and a wrapper materialsecured around the interior structure to form a rod with a circumferenceC2; wherein the wrapper material comprises a first portion welded to asecond portion of the wrapper material; wherein the interior structureis under compression by the wrapper material when the wrapper materialis secured around the interior structure; and wherein C1/C2 is in arange from 1.2 to
 6. 2. An aerosol-cooling element according to claim 1,wherein C1/C2 is in a range from 1.3 to 4, optionally in a range from1.4 to 2.5.
 3. An aerosol-cooling element according to claim 1, whereinthe first portion of the wrapper material is a region contiguous andparallel to a first edge of the wrapper material, and wherein the secondportion is a region contiguous and parallel to a second edge of thewrapper material.
 4. An aerosol-cooling element according claim 3,wherein the interior structure comprises a longitudinal axis and thesecond edge of the wrapper material is aligned at a non-zero angle tothe longitudinal axis.
 5. An aerosol-cooling element according to claim1, wherein the first portion is welded to the second portion via ametallic strip.
 6. An aerosol-cooling element according to claim 5,wherein the first portion is induction welded to the second portion. 7.An aerosol-cooling element according to claim 1, wherein the firstportion is ultrasonically welded to the second portion.
 8. Anaerosol-cooling element according to claim 1, wherein theaerosol-cooling element has a length between 7 mm and 28 mm.
 9. Anaerosol-cooling element according to claim 1, wherein theaerosol-cooling element has a diameter between 5 mm and 12 mm.
 10. Anaerosol-cooling element according to claim 1, wherein the wrappermaterial comprises a polymer, and optionally wherein the interiorstructure comprises polylactic acid.
 11. An aerosol-generating articlein the form of a rod, the aerosol-generating article comprising anaerosol-cooling element of claim
 1. 12. An aerosol-generating articleaccording to claim 11, wherein the aerosol-generating article comprisesan aerosol-forming substrate and the aerosol-cooling element is locateddownstream of the aerosol-forming substrate.